1. Field of the Invention
The present invention relates to an electrode unit for resistance welding.
2. Description of Background Information
The welding of a plurality of wires by use of a resistance welder is known and disclosed, for instance, in Japanese Unexamined Patent Application No. HEI 7-65927. In general, such a welding apparatus has a pair of platens that are positioned facing one another in a fastening-separating relationship. On one platen, a guiding member with a bottom and sides is provided, the bottom of which is integral with a fixed electrode that is electrically connected to the platen. On the other platen, a movable electrode is provided for applying voltage to a work positioned between the fixed electrode and the movable electrode. With this structure, resistance welding is carried out by nipping a work which is positioned between the surrounding guide members, the fixed electrode and the movable electrode, with substantial voltage being applied between the electrodes.
In the above-noted welder, each electrode is individually loaded on a platen, so that it is extremely difficult to accurately position the center of each electrode, when electrodes are changed according to the different types of work to be welded. Especially with wire harnesses, where integrated joint welding with many wires bundled, and then connected in a batch manner, is to be carried out, a considerable period of time is needed for initial start-up, due to frequent changing of electrodes. In addition, if the positioning of the electrodes is incorrect, there exists the possibility of failure and consequent damage to the electrodes and the like, because of interference between the movable electrode and the edge of the surrounding members.
The present invention was made in view of the above-mentioned problems, and with the object of providing an electrode unit for resistance welding capable of carrying out easy and fast exchange of platens.